There is an environmental efficiency case for clearing Britain’s railways of their remaining freight traffic (accounting for less than 5% of all goods moved in the UK anyway) and transferring it to large, 44-tonne trucks on free flowing roads.

The resulting space on the rails should be filled by faster and more frequent passengercarrying trains as part of a co-ordinated strategy to get people out of their private cars and on to public transport.

At first sight this may not look a very environmentally friendly solution to the problem of reducing harmful emissions, but in fact it could make very good sense – as I will seek to demonstrate. To many people, today’s truck looks very much like the ones of 50 years ago.

It basically uses the same propulsion system – a six cylinder diesel engine – and is engineered to deliver maximum efficiency when cruising at a steady speed. To many people’s eyes, a 1950’s juggernaut looks very much like a 2007 juggernaut.

But in reality a revolution has taken place over those 50 or so years. The modern truck is several times more efficient; it pollutes less, is much quieter and is dramatically more productive.

While modern trucks are bigger than they were at up to 44 tonnes gross weight now, compared with 24 tonnes then, there are actually fewer of them on the roads than there were 50 years ago.

Yes, in the 1950s there were around 450,000 trucks on British roads and they were responsible for around 32 billion tonne/kilometres of road freight per year. Today that number has actually fallen to around 430,000 trucks, yet they carry a whopping 163 billion tonne/kilometres – in short, five times as much goods carried on fewer trucks.

That’s due to much more efficient use of them. Indeed, our relatively high fuel prices may have contributed to the fact that British trucks are more efficiently operated than those in many other European countries.

That’s one reason why, over the same period, rail freight has collapsed from 37 billion tonne/kilometres a year – slightly more than was carried by road in 1950 – to only 22 billion tonne/kilometres now, or about only one eighth of that carried by road.

If we turn to the private car, over the same period as the number of trucks declined, the number of cars on our roads has mushroomed – up from around two million in 1950 to over 26 million this year.

What is more, and this is important, trucks are not used for leisure and pleasure; they are not used for ‘joy rides’. If a truck’s on the move then it’s because there’s a sound economic reason for it being so and – more often than not – it’s carrying a significant load. Yet the car is very often used for non-essential or discretionary journeys, and all-toofrequently it’s not well loaded at all; in fact its probably carrying just one person.

Now at this point we need to look at the diesel engine in more detail, for it is the on-going development of that which has brought much of the revolution in today’s trucks – and will continue to do so for the foreseeable future. The diesel engine is a very efficient power unit and it has been transformed into one of the cleanest. And despite all the talk of biofuels, hybrids, hydrogen and the like it’s the diesel which will be hauling most of the goods we need to sustain our daily lives for many years to come.

However you burn it, whether in a modern efficient truck or in a 10-year-old car, the inevitable fact is that every litre of diesel used in an internal combustion engine emits about 2.6kg of CO2 into the atmosphere. So the real answer is to make every litre of fuel burnt as productive as possible. And because of those efficiency gains I highlighted earlier, the overall emissions per tonne carried have fallen dramatically over the years.

Today’s diesel trucks burn about 40% less fuel (and therefore have a 40% smaller ‘carbon footprint’) per tonne of goods carried than they did only 25 years ago. Even more remarkably, for every litre of diesel burnt they now emit over 90% less particulate matter than they did then; in terms of harmful NOx emissions the number has fallen by over 80% in the same period.

More exotic new fuels may have a role in the arena of passenger carrying vehicles, both private and, increasingly, public. But diesel will very likely be the fuel which turns the wheels of the economy for many years to come. And giving those diesel-powered trucks the space to operate makes a lot of sense.

So here’s an alternative agenda for a greener British transport scene: invest in making high-speed rail and coach travel the attractive alternative to long-distance motoring, even if it means taking some freight off the rails. Let’s encourage heavier, better utilised trucks out there carrying the goods we all need in a clean and efficient manner – and let’s give them the space to operate.

A final plea: let’s also get the CO2 debate into perspective. According to studies, nature generates about 29 times the amount of CO2 as man, and CO2 itself is down the list of global warming gases – naturally occurring methane has 24 times more warming influence and ozone has 2,000 times more.

Let me quote from American writer Patrick Bedard: “The bottom line is this: all human contributions add up to a tiny share of the total greenhouse effect; between half-a-percent and one-and-a-half percent is science’s best estimate.

About half of that can be blamed on CO2 from all human sources…so all [vehicle] exhaust taken together amounts to some fraction of about half-of-onepercent of the greenhouse effect. Shaving that fraction is hopelessly out of scale with the problem.”

I could not put that better myself. Yes, we need to go on making our goods carriers cleaner and more productive; but no, we don’t need to be inventing all sorts of highly expensive and damaging new technologies to solve a problem over which we in reality have little control.